Method of manufacturing silent gears



May 30, 1933. .-w. LYTLE METHOD OF MANUFACTURING SILENT GEARS Original Filed Oct. 1, 1931 Patented May 30, 1933 ROBERT W. LYTLE, OF CINCINNATI, OHIO,

PATENT OFFICE ASSIGNOR TO THE FORMICA INSULATION COMPANY, OF CINCINNATI, OHIO, A CORPORATION OF OHIO METHOD OF MANUFACTURING SILENT GEARS Original application filed October 1, 1931, Serial No. 566,353. Divided and this application filed June 11, 1932. Serial No. 616,699.

This invention relates particularly to the manufacturing of wheels, or gears, composed largely, or entirely, if desired, of fibrous material impregnated with a binder adapted to be hardened by heat, the structure being consolidated under heat and pressure.

The primary object of the present invention is to provide a molded wheel of great strength, avoiding waste of materials in the manufacture.

The invention is illustrated in a preferred embodiment in the accompanying drawing, in which- Fig. 1 is a broken plan view of a. gearblank, or wheel, made in accordance with the invention; Fig. 2, a sectional view of the wheel; Fig. 3, a plan view of a modified form; and Fig. 4, a sectional view of the form shown in Fig. 3.

In accordance with the present invention, a wheel-center is formed by wrapping a strip of impregnated fabric upon itself so that the layers are concentric. with the axis of the wheel; forming a rim-portion of impregnated strips of fabric which lie in a plane at right angles to the axis of the wheel, and introducing the structure into a mold and consolidating the structure under heat and pressure.

The dies may be such as to produce the result shown in Fig. 2, in which the layers forming the hub and web portions remain substantially parallel with the axis of the wheel; or the dies may be such as to produce the effect illustrated in Fig. 4, in which the layers forming the web are folded into somewhat angular form, approximating more and more an acute V-shape as the rim is approached. The edge portions of the Vs become more or less parallel to and interlaced with the inner portions of the strips which form the rim, which, as stated, lie in a plane at right angles to the axis of the wheel.

Referring to Figs. 1 and 2, A designates a gear-blank comprising a metallic hub-center 1, a surrounding hub-portion of laminated stock 1*, a web-portion 1 and a rim 1.

The structure is formed by winding upon the metal member 1 a strip of fabric impregnated with a solution of resin adapted to harden under heat and pressure; by then winding upon the portion 1 a narrower tape impregnated with a binder of the same character; and by then applying rings of fabric impregnated with a binder of the same character to provide the rim 1.

The structure is introduced into a mold and consolidated under heat and pressure, the form of the dies being such as to produce the effect shown in Fig. 2.

The binder employed preferably is a phenolic condensation product, such as bakelite, adapted to harden under heat. In the operation of pressing in heated dies, the binder is converted to a hard, resistant condition. That is, it becomes infusible and strongly insoluble.

inch. In the pressing operation, the dies may be relieved, one or more times, to permit escape of gases. In the treatment in a heated bath or baths, it may be continued for a period of 30-60 hours; gases are permitted to escape and the gear-blank shrinks in such manner as to more firmly bind the hub-portion 1 upon the metal hub-portion 1. Preferably the outer circumferential surface of the member 1 is provided with projections, as indicated at 2. These projections may be formed by diagonal cross cuts, the cuts crossing each other.

Thus, the laminated structure is firmly secured to the metal bushing in such manner as to resist both torsional and lateral strains. If desired, the metal bushing may be omitted from the structure.

In the modification shown in Figs. 3 and 4, the gear-blank is designated A. It is shown as comprising a central bushing 3, a

hub-portion 3 a web-portion 3 and a riin 3. In this modification, the structure is formed as described above and consolidated in a heated mold provided with walls adapted, in the pressing operation, to force the edge portions of the tape forming the web to be directed more and more towards the rim, as the rim is approached. Thus, the strips forming the web are -folded into angular shape, somewhat resembling a V, the acuteness of the V becoming more and more pronounced as the rim is approached. The edge portions of the outer circles of the lamina'tions forming the web intermingle to a certain extent with the inner portions of the layers which form'the rim. The angular shape of the laminations make the web strongly resistant to side thrust, as Well as strongly resistant to radial forces.

- It may be remarked, also, that in the form shown in Fig. 2, the web is strongly resistant to lateral thrusts.

' Instead of a phenolic condensation prod uct, any suitable artificialresin adapted" to harden under heat and pressure may be employed, such as a suitable furfural resin, a 'resin of the ureaformaldehyde type, or the like.

In building up the rim of the structure, preparatory to molding, .one may employ segments of impregnated cloth, or one may employ an, impregnated fabric type with V- notches at one edge, permitting the tape to be Wound spirally with the layers "parallel to each other and at right angles to the axis of the wheel.

'The improved structure can be producedwith a minimum of waste. .Duek impregbe used to cover the built up structure pre- :Vious ly described. Thus, the finished gearblank will have askin'or covering" of fabric nated with a potentially reactive solution of bakelite and dried at moderate temperatures-maybe employed for forming the laminations. Any other suitable fabric may be employed. If desired, in assembling the structure, a

layer, or layers, ofiimpregn'ated fabric may concealing the laminations underneath.

The presentapplication constitutes a di; vision of my application Serial Number 566,353 filed'October 1, 1931.

'The foregoing detailed description has been given I for clearness of understanding only, and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly. as

permissible, in view of the prior art.

- What I regard as new, and desire to secure by Letters Patent, is: A

1. The process of forming a wheel which comprises: building a structure comprising a wheel-center comprising a metal sleeve, a

hub portion and a web formed by winding a strip in substantially concentric layersupon said sleeve, and a rim-structure hav- I ing its laminations in a plane substantiall at right angles to the axis of the whee. said layers and laminations being impregnated with a resin adapted to harden under heat; and introducing the structure into a mold and consolidating the same under heat and pressure to produce a hard, resistant product.

2. A process of forming a wheel which comprises: building a structure comprising a wheel-center having its laminations concentric with the axis of the wheel, and a rim-structure having its laminations in a plane substantially at right angles to the axis of the wheel, the laminations being impregnated with 'a resin adapted to harden under heat; and introducing the structure into and consolidating the same into a hard, resistant product in dies which have the effect of bending the edge-portions of the laminations of the web outwardly toward 

